This invention relates to a process and for introducing coffee aromas into an oil for flavoring a soluble coffee powder.
Soluble coffee powder is conventionally produced by freeze-drying or spray-drying of a coffee extract obtained after evaporation by countercurrent percolation of an extraction liquid through cells filled with ground roasted coffee.
One of the major problems of this type of process lies in the fact that the product obtained does not have the flavor of a roasted coffee, which is particularly due, on the one hand, to the extraction process and, on the other hand, to the steps of evaporation and freeze-drying or spray-drying, which inevitably involve significant losses of flavor.
Various solutions have been proposed in which an oil, generally a coffee oil, is enriched with coffee aromas and then sprayed onto the soluble coffee powder or incorporated in a jar filled with soluble coffee powder.
The principal aroma source known and used for this purpose are the aromas released from ground roasted coffee.
One of the main problems to be solved in a process of this type is to be able to transfer the coffee aromas from the frost to the oil support.
French Patent No. 2,336,088, for example, describes a process in which an inert gas circulates through a ground roasted coffee. This inert gas becomes charged with aromas and a frost is formed by condensation of the carbon dioxide entrained, moisture and aromas. This frost is then contacted with an oil under predetermined temperature and pressure conditions so that the oil recovers part of the aromas present in the frost. The oil obtained may then be incorporated in a soluble coffee powder.
In the process described in the French Patent, a frost containing coffee aromas and carbon dioxide is placed in a container in which prevail a temperature above 0.degree. C. and an absolute pressure above 35 bar, the water present in the frost is eliminated, and a certain quantity of liquid oil is then introduced into the container under pressure, the temperature and pressure conditions being such that the oil is above its freezing point.
The pressure is then slowly released, the oil being kept in the liquid state. An oil charged with coffee aromas is thus obtained.
This oil charged with aromas may then be used to flavor a soluble coffee powder, for example by spraying the oil onto the powder.
In another process which is described in European Patent Application No. 92104622.3 , a step of contacting the oil with a frost is used to free the frost from these undesirable aromas. In a second step, the liquid residue obtained, which is still charged with aromas, is contacted with a second oil, which is the oil to be used to flavor the soluble coffee powder, the first oil being eliminated.
At all events, the method of transferring aromas from a frost to an oil described in French Patent No. 2,336,088 is unsatisfactory in many respects because it does not allow continuous production. Secondly, the conditions under which the aromas are transferred from the frost to the oil are not controlled. Finally, this known method has to be carried out under high pressure.